Where and do Calvin, Charles Wallace, and Meg go with Mrs. Whatsit, Mrs. Who, and Mrs. Which

This depends on what chapter you are referring to. The first place they visit is the planet Uriel: it isdescribed as the third planet of the star Malak.

They go to Uriel, the third planet of the star Malak in the spiral nebula Messier 101. The go becuase they want to save their father.